Carbon black burner construction

ABSTRACT

An improved carbon black burner construction utilizing multiple arrays of gas jets spaced from the oil discharge orifice and including a venturi atomizing tip just prior to the oil discharge orifice improves the light transmittance of a benzene extract from nonstaining large particle size, high structure carcass carbon blacks.

United States Patent Stubblefield et al. 51 Mar. 21, 1972 CARBON BLACKBURNER 4 [56 References Cited UNITED STATES PATENTS [72] inventors:Charles David Stubblefield, Baton Rouge, 1 952 236 3/1934 Clawsonmm"mug/423 X Li; Lee wells 3mg", 2,965,163 12/1960 Lange et al...239/4l9.3 x 73 Assignee; Huber Corporaion, Berger 2,990,749 7/196!Thiers et all. 239/4193 X 22] Filedl J 1970 Primary Examiner- Lloyd L.King [21] PP 1,092 Attorney-Harold H. Flanders [57] ABSTRACT 52 us. Cl..239/419.3, 239/423 An improved carbon black burner constructionutilizing [5]] Int. Cl ..F23d 11/16 tiple arrays of gas jets Spaced fromthe o discharge orifice [58] Field ofSearch ..239/423,424,434.5,290,296,and including 3 venturi atgmizing tip just prim t0 the oil /4193discharge orifice improves the light transmittance of a benzene extractfrom nonstaining large particle size, high structure carcass carbonblacks.

4 ain 1 ra in Figure v BACKGROUND OF THE INVENTION In general, thepresent invention relates to burner construction and more particularlyto an improved carbon black burner construction.

A frequently employed test in the carbon black industry is the"Discoloration of Benzene by Carbon Black" designated ASTM: D16 1 8-65T.Briefly, this test constitutes a determination of the degree ofdiscoloration of benzene by carbon black and hydrocarbons adhering to orassociated with the carbon black as produced by means of .aspectrophotometer expressed in percentage light transmission at a wavelength of 425 millimircrons, assuming the absorption cell of thespectrophotometer filled with boiled, filtered benzene to have 100percent transmission.

High benzene discoloration with a corresponding decrease in itspercenttransmittance as determined by ASTM: D1618 may result when coke ispresent in the carbon black manufacturing process. Coke often forms onand around the tip of the burner structure as a result of variations infurnace pressures in this region. These pressure variations cause smalloil droplets to come into contact with the vapor tube tip and result inthe formation of a cone of coke. The production of excess coke may bereduced or eliminated by altering the air flow patterns and otherconditions producing unstable combustion near the burner. However, inaltering the conditions in the area surrounding the burner it isnecessary to do so in such a way as to not interfere with the obtainingof the desired level of structure for the carbon black or in a way whichalters in an undesired way the carbon black particles size. Anadditional coking problem may also exist internally within the burnerstructures of the prior art. A significant factor causing this problemin prior art structures is the mixing of the atomizing media with thehot oil in a chamber external to the main body of the burner assembly.The intimate mixture of air with the oil to be atomized may then ofnecessity be forced to flow the entire burner length before beingsprayed out of the nozzle. The intimate contact provided results in aprogressive buildup of coke within the burner structure which graduallyreduces the flow of atomizing air or gas and continuously degrades theoperation of the burner.

SUMMARY OF THE INVENTION Accordingly, it is an object of the presentinvention to provide a new and highly effective carbon black burnerconstruction which overcomes the deficiencies of the prior art asdescribed above.

It is a further object of the present invention to provide a carbonblack burner construction capable of producing a carbon black whichexhibits nonstaining properties.

Another object of the present invention is to provide a carbon blackburner construction which provides a more stable flame and combustionconditions in the areas surrounding the burner to reduce the formationof coke.

An additional object of the present invention is to provide a carbonblack burner construction capable of achieving carbon black of thedesired structure and particle size with low discoloration of benzenewhen tested according to ASTM: D161 8-651.

Another object of the present invention is to provide a carbon blackburner construction in which internal coking within the burner isminimized.

Other objects and a fuller understanding of the present invention may behad by referring to the following description and claims taken inconjunction with the accompanying drawmg.

The present invention overcomes the deficiencies of the prior art andachieves its objectives by providing for multiple arrays of gas jetsproperly spaced from the oil discharge orifice and by the provision ofan atomizing venturi tip just prior to the oil discharge orifice.

BRIEF DESCRIPTION OF THE DRAWING In order to facilitate theunderstanding of the present invention reference will now be made to theappended drawing of a preferred embodiment of the present invention. Thedrawing should not be construed as limiting the invention but isexemplary only.

In the drawing:

The FIGURE is a partial cross-sectional representation of a preferredembodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT While there is no general theoryavailable enabling one to define in detail the effects of variousmodifications in burner structure, particularly with regard to themanner in which such modifications in burner structure may effect theproperties of the carbon black produced, it has been found that theburner construction defined below is particularly advantageous for theproduction of nonstaining large particle size, high structure carcasscarbon blacks which when tested according to ASTM: D1618 exhibit lowbenzene discoloration and high transmittance. Briefly, in accordancewith the present invention, the preferred embodiment of the presentinvention is shown in the appended drawing. Gas, indicated in general bythe arrow G, passes down the space 10 defined by outer concentric tubingwall 18 and tubing 22 to exit at a plurality of jet ports 12 in the tipof the burner nozzle 14. Gas also flows out a plurality of gas jets 16spaced a distance designated L behind the first plurality of jet ports12. The additional gas jets 16 in the outer tubing wall 18 provide forstructural and benzene discoloration properties intermediate to thosewhich would be obtained were a plurality of jets to be placed in the tip14 only or if a plurality of gas jets were to be placed a greaterdistance back in the burner without the use of a group of gas jets inthe tip 14 of the burner. A baffle wall 20 may optionally be attached tothe outer wall 18 and may be utilized to control the flow of the gas toprovide cooling to the burner tip 14 while bringing the gas to the exitgas jets 12 and 16. An inner-concentric tube 22 defines the area throughwhich the oil feedstock flows as indicated schematically by the arrowdesignated 0. The oil tubing 22 ends in orifice 24 at the tip of nozzle14. The orifice which acts as the oil discharge orifice 24 has adiameter designated D. Centrally disposed within the oil tubing 22 is atube 26 through which air, gas or other suitable atomizing fluid maypass. The tubing ends at a venturi tip designated 28 closely adjacent,proximate to and directly behind oil discharge orifice 24. The flow ofatomizing fluid indicated by the designation A passing through tube 26ending at the venturi tip 28 serves to atomize the oil providing amixture of oil and gas or air at the tip of the nozzle 14.

In operation, the flow of gas G passes through the outer peripheraltubing space 10 and exits at gas jets l2 and 16. An ignition providingthe desired flow pattern and air pressure patterns in the region of thenozzle to prevent coking and to provide the desired particle size andstructure characteristics of the black is produced.

The reasons that this combination of gas jet ports produces a higherlevel of structure than, for example, burners in which all of the gastips are in the tips at positions corresponding to those indicated at12, and at the same time produces a lower degree of discoloration ofbenzene by carbon black produced at the same or equal levels of surfacearea, particle size and structure than produced with the use alone ofgas jets in positions analogous to those indicated at 16 but furtherback in the burner structure as taught by prior art construction is notfully understood nor theoretically explainable in its entirety. Sufficeit to say, however, that carbon black having the desired properties,structure, particle size, surface area and producing the desiredtransmittance when tested by the discoloration of benzene in accord withASTM: D1618 are obtained by the presently described structure.

Oil feedstock flowing through tube 22 and indicated by passes down thetube 22 to the region of the venturi tip 28. Air, gas, a combination ofair and gas or other suitable atomizing fluid, indicated by A, passingthrough venturi tube 26 enters the oil stream to produce an atomizingaction beginning in the region just behind and adjacent to oil dischargeorifice 24. The oil being atomized is discharged through orifice 24 andthe process of carbon black production thereafter efiected in accordwith conventional and known techniques.

It is of the utmost importance in order to control the air pressurepattern and distribution and such other factors as may yet beundetermined but which nevertheless affect the structuralcharacteristics, particle size and surface area of carbon blacks and theformation of coke, that the relationship of the gas jets to the oilorifice be well defined. In particular it has been found that thelocation of the multiplicity of gas jets 16 should be a distance Lbehind the plurality of gas jets 12 in nozzle 14 which is not greaterthan 30 times the diameter D of oil discharge orifice 24 and preferablynot greater than 15 times thediameter D of the oil discharge orifice 24.While obviously variations outside of this desired limit may be employedwith more or less success depending upon the particular propertiesdesired and considered crucial in a particular application the presentlydescribed arrangement has been found particularly advantageous. Fortypical dimensions, the diameter of the oil orifice may be on the orderof 0.02 to 0.25 inches in diameter and it has been found desirable toplace the additional gas jets 16 approximately 3 inches behind the tipof the nozzle 14.

In general, each bank or circumferential group of gas jets will consistof six or more orifices designated 12 and 16 with each orifice having anapproximate diameter of one-eighth inch.

The adjustment of venturi nozzles 28 may be varied slightly up and downthe length of the oil tubing 22 but it is preferable to place it fromapproximately 0.3 to 0.5 inch from or otherwise as close as practicallypossible to the oil discharge orifice 24 since it has been found thatthe short exposure time of the atomized oil reduces coking and the highvelocity of the atomizing fluid helps keep the nozzles scoured free ofcoke deposits.

in all cases, structure control may of course be achieved to some extentby manipulation of oil/gas ratios and the atomizing air rate along withother factors that are known in the art.

The advantage of the present apparatus is found primarily in its abilityto achieve the desired properties of a non-staining large particle size,high structure carbon black which has low benzene discoloration and hightransmittance.

In addition, of course, the simplified design evolved from placing theatomizing tip 28 closely adjacent the oil discharge orifice 24 providesfor both economies of engineering design and economies derived fromreduced maintenance costs and prevention of lost time by shutdown due tocoking. Further, the atomizing air or gas settings required to producethe desired property remain more nearly constant and require lessoperator attention with the present design. In addition, a moreconsistent oil spray pattern is obtained for a longer period of timebecause of the prevention, at least in part, of the formation of cokingdeposits thereby resulting in a product of improved uniformity. Perhapseven more important from a practical standpoint, the present burnerdesign described above enables a reduction in the required maintenancedue to coking internally within the burner of over 100 fold with theresultant increase in net production time for each burner.

Without the use of multiple banks of gas ports high structure, largeparticle size blacks in the past have tended to exhibit high benzenediscoloration. This condition has frequently caused the carbon black tofail to meet required specifications. However, by use of the presentlydescribed burners structure set forth above, it is possible to avoidthis problem while producing a carbon black having the desiredstructural characteristics. Obviously, of course, the burner is notlimited to the production of only carbon black having specifiedcharacteristics.

It should be understood that other means of atomization may be employedin the same mixing chamber region without departing from the spirit andscope of the present invention. It should also be understood that thedimensions and positioning of elements other than as defined in theattached claims are optional and may be varied by those skilled in theart over a wide range, and are given here merely for purposes ofillustration.

Furthermore, although a specific preferred embodiment of the presentinvention has been described in the detailed description above, theabove description is not intended to limit the invention to theparticular forms or embodiments disclosed herein, since they are to berecognized as illustrative rather than restrictive. it will be obviousto those skilled in the art that the invention is not so limited. Theinvention is declared to cover all changes and modifications to thespecific embodiments of the invention herein disclosed for purposes ofillustration which do not constitute departures from the spirit andscope of the invention.

We claim:

1. An improved carbon black fuel burner construction for producing acontrolled structure, high particle size nonstaining carbon blackproducing a low degree of discoloration of benzene when tested accordingto ASTM: Dl6l8-65T, said burner being of the type which provides for theatomizing of an oil feedstock within an internal mixing chamber fordischarge at an oil discharge orifice, which is circumferentiallysurrounded at the nozzle surrounding said oil discharge orifice by aplurality of combustion gas jets, wherein the improvement comprises: anadditional plurality of circumferentially disposed combustion gas jets,positioned on the burner on the side of said first mentioned pluralityof combustion gas jets opposite said oil discharge orifice, at adistance behind said first mentioned plurality of combustion gas jetswhich is less than 30 times the diameter of said oil discharge orifice.

2. The improvement of the burner construction of claim 1 in which saidadditional plurality of circumferentially disposed combustion gas jetsis positioned on the burner on the side of said first mentionedplurality of combustion gas jets opposite said oil discharge orifice, ata distance behind said first mentioned plurality of combustion gas jetswhich is less than 15 times the diameter of said oil discharge orifice.

3. The improvement of the burner construction of claim 2 which furthercomprises the provision of said internal mixing chamber proximatelyadjacent to said oil discharge orifice of said burner, whereby internalcoking of said burner is reduced.

4. The improvement of the burner construction of claim 3 which furthercomprises the provision of a venturi tip within said internal mixingchamber proximate to said first mentioned plurality of combustion gasjets and adjacent to said oil discharge orifice of said burner and atleast 10 times the diameter of said oil discharge orifice from saidadditional plurality of circumferentially disposed combustion gas jets.

1. An improved carbon black fuel burner construction for producing acontrolled structure, high particle size nonstaining carbon blackproducing a low degree of discoloration of benzene when tested accordingto ASTM: D1618-65T, said burner being of the type which provides for theatomizing of an oil feedstock within an internal mixing chamber fordischarge at an oil discharge orifice, which is circumferentiallysurrounded at the nozzle surrounding said oil discharge orifice by aplurality of combustion gas jets, wherein the improvement comprises: anadditional plurality of circumferentially disposed combustion gas jets,positioned on the burner on the side of said first mentioned pluralityof combustion gas jets opposite said oil discharge orifice, at adistance behind said first mentioned plurality of combustion gas jetswhich is less than 30 times the diameter of said oil discharge orifice.2. The improvement of the burner construction of claim 1 in which saidadditional plurality of circumferentially disposed combustion gas jetsis positioned on the burner on the side of said first mentionedplurality of combustion gas jets opposite said oil discharge orifice, ata distance behind said first mentioned plurality of combustion gas jetswhich is less than 15 times the diameter of said oil discharge orifice.3. The improvement of the burner construction of claim 2 which furthercomprises the provision of said internal mixing chamber proximatelyadjacent to said oil discharge orifice of said burner, whereby internalcoking of said burner is reduced.
 4. The improvement of the burnerconstruction of claim 3 which further comprises the provision of aventuri tip within said internal mixing chamber proximate to said firstmentioned pluraliTy of combustion gas jets and adjacent to said oildischarge orifice of said burner and at least 10 times the diameter ofsaid oil discharge orifice from said additional plurality ofcircumferentially disposed combustion gas jets.